device.c

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/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 Bert Vermeulen <bert@biot.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <glib.h>
#include <stdio.h>
#include <string.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"
#include "scpi.h"

/** @cond PRIVATE */
#define LOG_PREFIX "device"
/** @endcond */

/**
 * @file
 *
 * Device handling in libsigrok.
 */

/**
 * @defgroup grp_devices Devices
 *
 * Device handling in libsigrok.
 *
 * @{
 */

/**
 * Allocate and initialize a new struct sr_channel and add it to sdi.
 *
 * @param[in] sdi The device instance the channel is connected to.
 *                Must not be NULL.
 * @param[in] index @copydoc sr_channel::index
 * @param[in] type @copydoc sr_channel::type
 * @param[in] enabled @copydoc sr_channel::enabled
 * @param[in] name @copydoc sr_channel::name
 *
 * @return A new struct sr_channel*.
 *
 * @private
 */
SR_PRIV struct sr_channel *sr_channel_new(struct sr_dev_inst *sdi,
                int index, int type, gboolean enabled, const char *name)
{
        struct sr_channel *ch;

        ch = g_malloc0(sizeof(*ch));
        ch->sdi = sdi;
        ch->index = index;
        ch->type = type;
        ch->enabled = enabled;
        if (name && *name)
                ch->name = g_strdup(name);

        sdi->channels = g_slist_append(sdi->channels, ch);

        return ch;
}

/**
 * Release a previously allocated struct sr_channel.
 *
 * @param[in] ch Pointer to struct sr_channel.
 *
 * @private
 */
SR_PRIV void sr_channel_free(struct sr_channel *ch)
{
        if (!ch)
                return;
        g_free(ch->name);
        g_free(ch->priv);
        g_free(ch);
}

/**
 * Wrapper around sr_channel_free(), suitable for glib iterators.
 *
 * @private
 */
SR_PRIV void sr_channel_free_cb(void *p)
{
        sr_channel_free(p);
}

/**
 * Set the name of the specified channel.
 *
 * If the channel already has a different name assigned to it, it will be
 * removed, and the new name will be saved instead.
 *
 * @param[in] channel The channel whose name to set. Must not be NULL.
 * @param[in] name The new name that the specified channel should get.
 *                 A copy of the string is made.
 *
 * @return SR_OK on success, or SR_ERR_ARG on invalid arguments.
 *
 * @since 0.3.0
 */
SR_API int sr_dev_channel_name_set(struct sr_channel *channel,
                const char *name)
{
        if (!channel)
                return SR_ERR_ARG;
        if (!name || !*name)
                return SR_ERR_ARG;

        g_free(channel->name);
        channel->name = g_strdup(name);

        return SR_OK;
}

/**
 * Enable or disable a channel.
 *
 * @param[in] channel The channel to enable or disable. Must not be NULL.
 * @param[in] state TRUE to enable the channel, FALSE to disable.
 *
 * @return SR_OK on success or SR_ERR on failure. In case of invalid
 *         arguments, SR_ERR_ARG is returned and the channel enabled state
 *         remains unchanged.
 *
 * @since 0.3.0
 */
SR_API int sr_dev_channel_enable(struct sr_channel *channel, gboolean state)
{
        int ret;
        gboolean was_enabled;
        struct sr_dev_inst *sdi;

        if (!channel)
                return SR_ERR_ARG;

        sdi = channel->sdi;
        was_enabled = channel->enabled;
        channel->enabled = state;
        if (!state != !was_enabled && sdi->driver
                        && sdi->driver->config_channel_set) {
                ret = sdi->driver->config_channel_set(
                        sdi, channel, SR_CHANNEL_SET_ENABLED);
                /* Roll back change if it wasn't applicable. */
                if (ret != SR_OK)
                        return ret;
        }

        return SR_OK;
}

/**
 * Returns the next enabled channel, wrapping around if necessary.
 *
 * @param[in] sdi The device instance the channel is connected to.
 *                Must not be NULL.
 * @param[in] cur_channel The current channel.
 *
 * @return A pointer to the next enabled channel of this device.
 *
 * @private
 */
SR_PRIV struct sr_channel *sr_next_enabled_channel(const struct sr_dev_inst *sdi,
                struct sr_channel *cur_channel)
{
        struct sr_channel *next_channel;
        GSList *l;

        next_channel = cur_channel;
        do {
                l = g_slist_find(sdi->channels, next_channel);
                if (l && l->next)
                        next_channel = l->next->data;
                else
                        next_channel = sdi->channels->data;
        } while (!next_channel->enabled);

        return next_channel;
}

/**
 * Compare two channels, return whether they differ.
 *
 * The channels' names and types are checked. The enabled state is not
 * considered a condition for difference. The test is motivated by the
 * desire to detect changes in the configuration of acquisition setups
 * between re-reads of an input file.
 *
 * @param[in] ch1 First channel.
 * @param[in] ch2 Second channel.
 *
 * @return TRUE upon differences or unexpected input, FALSE otherwise.
 *
 * @private
 */
SR_PRIV gboolean sr_channels_differ(struct sr_channel *ch1, struct sr_channel *ch2)
{
        if (!ch1 || !ch2)
                return TRUE;

        if (ch1->type != ch2->type)
                return TRUE;
        if (strcmp(ch1->name, ch2->name))
                return TRUE;

        return FALSE;
}

/**
 * Compare two channel lists, return whether they differ.
 *
 * Listing the same set of channels but in a different order is considered
 * a difference in the lists.
 *
 * @param[in] l1 First channel list.
 * @param[in] l2 Second channel list.
 *
 * @return TRUE upon differences or unexpected input, FALSE otherwise.
 *
 * @private
 */
SR_PRIV gboolean sr_channel_lists_differ(GSList *l1, GSList *l2)
{
        struct sr_channel *ch1, *ch2;

        while (l1 && l2) {
                ch1 = l1->data;
                ch2 = l2->data;
                l1 = l1->next;
                l2 = l2->next;
                if (!ch1 || !ch2)
                        return TRUE;
                if (sr_channels_differ(ch1, ch2))
                        return TRUE;
                if (ch1->index != ch2->index)
                        return TRUE;
        }
        if (l1 || l2)
                return TRUE;

        return FALSE;
}

/**
 * Allocate and initialize a new channel group, and add it to sdi.
 *
 * @param[in] sdi The device instance the channel group is connected to.
 *                Optional, can be NULL.
 * @param[in] name @copydoc sr_channel_group::name
 * @param[in] priv @copydoc sr_channel_group::priv
 *
 * @return A pointer to a new struct sr_channel_group, NULL upon error.
 *
 * @private
 */
SR_PRIV struct sr_channel_group *sr_channel_group_new(struct sr_dev_inst *sdi,
        const char *name, void *priv)
{
        struct sr_channel_group *cg;

        cg = g_malloc0(sizeof(*cg));
        if (name && *name)
                cg->name = g_strdup(name);
        cg->priv = priv;

        if (sdi)
                sdi->channel_groups = g_slist_append(sdi->channel_groups, cg);

        return cg;
}

/**
 * Release a previously allocated struct sr_channel_group.
 *
 * @param[in] cg Pointer to struct sr_channel_group.
 *
 * @private
 */
SR_PRIV void sr_channel_group_free(struct sr_channel_group *cg)
{
        if (!cg)
                return;

        g_free(cg->name);
        g_slist_free(cg->channels);
        g_free(cg->priv);
        g_free(cg);
}

/**
 * Wrapper around sr_channel_group_free(), suitable for glib iterators.
 *
 * @private
 */
SR_PRIV void sr_channel_group_free_cb(void *cg)
{
        return sr_channel_group_free(cg);
}

/**
 * Determine whether the specified device instance has the specified
 * capability.
 *
 * @param sdi Pointer to the device instance to be checked. Must not be NULL.
 *            If the device's 'driver' field is NULL (virtual device), this
 *            function will always return FALSE (virtual devices don't have
 *            a hardware capabilities list).
 * @param[in] key The option that should be checked for is supported by the
 *            specified device.
 *
 * @retval TRUE Device has the specified option.
 * @retval FALSE Device does not have the specified option, invalid input
 *         parameters or other error conditions.
 *
 * @since 0.2.0
 */
SR_API gboolean sr_dev_has_option(const struct sr_dev_inst *sdi, int key)
{
        GVariant *gvar;
        const int *devopts;
        gsize num_opts, i;
        int ret;

        if (!sdi || !sdi->driver || !sdi->driver->config_list)
                return FALSE;

        if (sdi->driver->config_list(SR_CONF_DEVICE_OPTIONS,
                                &gvar, sdi, NULL) != SR_OK)
                return FALSE;

        ret = FALSE;
        devopts = g_variant_get_fixed_array(gvar, &num_opts, sizeof(int32_t));
        for (i = 0; i < num_opts; i++) {
                if ((devopts[i] & SR_CONF_MASK) == key) {
                        ret = TRUE;
                        break;
                }
        }
        g_variant_unref(gvar);

        return ret;
}

/**
 * Enumerate the configuration options of the specified item.
 *
 * @param driver Pointer to the driver to be checked. Must not be NULL.
 * @param sdi Pointer to the device instance to be checked. May be NULL to
 *            check driver options.
 * @param cg Pointer to a channel group, if a specific channel group is to
 *           be checked. Must be NULL to check device-wide options.
 *
 * @return A GArray * of enum sr_configkey values, or NULL on invalid
 *         arguments. The array must be freed by the caller using
 *         g_array_free().
 *
 * @since 0.4.0
 */
SR_API GArray *sr_dev_options(const struct sr_dev_driver *driver,
        const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
{
        GVariant *gvar;
        const uint32_t *opts;
        uint32_t opt;
        gsize num_opts, i;
        GArray *result;

        if (!driver || !driver->config_list)
                return NULL;

        if (sdi && sdi->driver != driver)
                return NULL;

        if (driver->config_list(SR_CONF_DEVICE_OPTIONS, &gvar, sdi, cg) != SR_OK)
                return NULL;

        opts = g_variant_get_fixed_array(gvar, &num_opts, sizeof(uint32_t));

        result = g_array_sized_new(FALSE, FALSE, sizeof(uint32_t), num_opts);

        for (i = 0; i < num_opts; i++) {
                opt = opts[i] & SR_CONF_MASK;
                g_array_insert_val(result, i, opt);
        }

        g_variant_unref(gvar);

        return result;
}

/**
 * Enumerate the configuration capabilities supported by a device instance
 * for a given configuration key.
 *
 * @param sdi Pointer to the device instance to be checked. Must not be NULL.
 *            If the device's 'driver' field is NULL (virtual device), this
 *            function will always return FALSE (virtual devices don't have
 *            a hardware capabilities list).
 * @param cg Pointer to a channel group, if a specific channel group is to
 *           be checked. Must be NULL to check device-wide options.
 * @param[in] key The option that should be checked for is supported by the
 *            specified device.
 *
 * @retval A bitmask of enum sr_configcap values, which will be zero for
 *         invalid inputs or if the key is unsupported.
 *
 * @since 0.4.0
 */
SR_API int sr_dev_config_capabilities_list(const struct sr_dev_inst *sdi,
                const struct sr_channel_group *cg, const int key)
{
        GVariant *gvar;
        const int *devopts;
        gsize num_opts, i;
        int ret;

        if (!sdi || !sdi->driver || !sdi->driver->config_list)
                return 0;

        if (sdi->driver->config_list(SR_CONF_DEVICE_OPTIONS,
                                &gvar, sdi, cg) != SR_OK)
                return 0;

        ret = 0;
        devopts = g_variant_get_fixed_array(gvar, &num_opts, sizeof(int32_t));
        for (i = 0; i < num_opts; i++) {
                if ((devopts[i] & SR_CONF_MASK) == key) {
                        ret = devopts[i] & ~SR_CONF_MASK;
                        break;
                }
        }
        g_variant_unref(gvar);

        return ret;
}

/**
 * Allocate and init a new user-generated device instance.
 *
 * @param vendor Device vendor.
 * @param model Device model.
 * @param version Device version.
 *
 * @retval struct sr_dev_inst *. Dynamically allocated, free using
 *         sr_dev_inst_free().
 */
SR_API struct sr_dev_inst *sr_dev_inst_user_new(const char *vendor,
                const char *model, const char *version)
{
        struct sr_dev_inst *sdi;

        sdi = g_malloc0(sizeof(*sdi));

        sdi->vendor = g_strdup(vendor);
        sdi->model = g_strdup(model);
        sdi->version = g_strdup(version);
        sdi->inst_type = SR_INST_USER;

        return sdi;
}

/**
 * Add a new channel to the specified device instance.
 *
 * @param[in] sdi Device instance to use. Must not be NULL.
 * @param[in] index @copydoc sr_channel::index
 * @param[in] type @copydoc sr_channel::type
 * @param[in] name @copydoc sr_channel::name
 *
 * @return SR_OK Success.
 * @return SR_OK Invalid argument.
 */
SR_API int sr_dev_inst_channel_add(struct sr_dev_inst *sdi, int index, int type, const char *name)
{
        if (!sdi || sdi->inst_type != SR_INST_USER || index < 0)
                return SR_ERR_ARG;

        if (!sr_channel_new(sdi, index, type, TRUE, name))
                return SR_ERR_DATA;

        return SR_OK;
}

/**
 * Free device instance struct created by sr_dev_inst().
 *
 * @param sdi Device instance to free. If NULL, the function will do nothing.
 *
 * @private
 */
SR_PRIV void sr_dev_inst_free(struct sr_dev_inst *sdi)
{
        struct sr_channel *ch;
        GSList *l;

        if (!sdi)
                return;

        for (l = sdi->channels; l; l = l->next) {
                ch = l->data;
                sr_channel_free(ch);
        }
        g_slist_free(sdi->channels);
        g_slist_free_full(sdi->channel_groups, sr_channel_group_free_cb);

        if (sdi->session)
                sr_session_dev_remove(sdi->session, sdi);

        g_free(sdi->vendor);
        g_free(sdi->model);
        g_free(sdi->version);
        g_free(sdi->serial_num);
        g_free(sdi->connection_id);
        g_free(sdi);
}

#ifdef HAVE_LIBUSB_1_0

/**
 * Allocate and init a struct for a USB device instance.
 *
 * @param[in] bus @copydoc sr_usb_dev_inst::bus
 * @param[in] address @copydoc sr_usb_dev_inst::address
 * @param[in] hdl @copydoc sr_usb_dev_inst::devhdl
 *
 * @return The struct sr_usb_dev_inst * for USB device instance.
 *
 * @private
 */
SR_PRIV struct sr_usb_dev_inst *sr_usb_dev_inst_new(uint8_t bus,
                        uint8_t address, struct libusb_device_handle *hdl)
{
        struct sr_usb_dev_inst *udi;

        udi = g_malloc0(sizeof(*udi));
        udi->bus = bus;
        udi->address = address;
        udi->devhdl = hdl;

        return udi;
}

/**
 * Free struct sr_usb_dev_inst * allocated by sr_usb_dev_inst().
 *
 * @param usb The struct sr_usb_dev_inst * to free. If NULL, this
 *            function does nothing.
 *
 * @private
 */
SR_PRIV void sr_usb_dev_inst_free(struct sr_usb_dev_inst *usb)
{
        g_free(usb);
}

/**
 * Wrapper for g_slist_free_full() convenience.
 *
 * @private
 */
SR_PRIV void sr_usb_dev_inst_free_cb(gpointer p)
{
        sr_usb_dev_inst_free(p);
}
#endif

#ifdef HAVE_SERIAL_COMM

/**
 * Allocate and init a struct for a serial device instance.
 *
 * Both parameters are copied to newly allocated strings, and freed
 * automatically by sr_serial_dev_inst_free().
 *
 * @param[in] port OS-specific serial port specification. Examples:
 *                 "/dev/ttyUSB0", "/dev/ttyACM1", "/dev/tty.Modem-0", "COM1".
 *                 Must not be NULL.
 * @param[in] serialcomm A serial communication parameters string, in the form
 *              of <speed>/<data bits><parity><stopbits>, for example
 *              "9600/8n1" or "600/7o2". This is an optional parameter;
 *              it may be filled in later. Can be NULL.
 *
 * @return A pointer to a newly initialized struct sr_serial_dev_inst,
 *         or NULL on error.
 *
 * @private
 */
SR_PRIV struct sr_serial_dev_inst *sr_serial_dev_inst_new(const char *port,
                const char *serialcomm)
{
        struct sr_serial_dev_inst *serial;

        serial = g_malloc0(sizeof(*serial));
        serial->port = g_strdup(port);
        if (serialcomm)
                serial->serialcomm = g_strdup(serialcomm);

        return serial;
}

/**
 * Free struct sr_serial_dev_inst * allocated by sr_serial_dev_inst().
 *
 * @param serial The struct sr_serial_dev_inst * to free. If NULL, this
 *               function will do nothing.
 *
 * @private
 */
SR_PRIV void sr_serial_dev_inst_free(struct sr_serial_dev_inst *serial)
{
        if (!serial)
                return;

        g_free(serial->port);
        g_free(serial->serialcomm);
        g_free(serial);
}
#endif

/** @private */
SR_PRIV struct sr_usbtmc_dev_inst *sr_usbtmc_dev_inst_new(const char *device)
{
        struct sr_usbtmc_dev_inst *usbtmc;

        usbtmc = g_malloc0(sizeof(*usbtmc));
        usbtmc->device = g_strdup(device);
        usbtmc->fd = -1;

        return usbtmc;
}

/** @private */
SR_PRIV void sr_usbtmc_dev_inst_free(struct sr_usbtmc_dev_inst *usbtmc)
{
        if (!usbtmc)
                return;

        g_free(usbtmc->device);
        g_free(usbtmc);
}

/**
 * Get the list of devices/instances of the specified driver.
 *
 * @param driver The driver to use. Must not be NULL.
 *
 * @return The list of devices/instances of this driver, or NULL upon errors
 *         or if the list is empty.
 *
 * @since 0.2.0
 */
SR_API GSList *sr_dev_list(const struct sr_dev_driver *driver)
{
        if (driver && driver->dev_list)
                return driver->dev_list(driver);
        else
                return NULL;
}

/**
 * Clear the list of device instances a driver knows about.
 *
 * @param driver The driver to use. This must be a pointer to one of
 *               the entries returned by sr_driver_list(). Must not be NULL.
 *
 * @retval SR_OK Success.
 * @retval SR_ERR_ARG Invalid driver.
 *
 * @since 0.2.0
 */
SR_API int sr_dev_clear(const struct sr_dev_driver *driver)
{
        if (!driver) {
                sr_err("Invalid driver.");
                return SR_ERR_ARG;
        }

        if (!driver->context) {
                /*
                 * Driver was never initialized, nothing to do.
                 *
                 * No log message since this usually gets called for all
                 * drivers, whether they were initialized or not.
                 */
                return SR_OK;
        }

        /* No log message here, too verbose and not very useful. */

        return driver->dev_clear(driver);
}

/**
 * Open the specified device instance.
 *
 * If the device instance is already open (sdi->status == SR_ST_ACTIVE),
 * SR_ERR will be returned and no re-opening of the device will be attempted.
 *
 * If opening was successful, sdi->status is set to SR_ST_ACTIVE, otherwise
 * it will be left unchanged.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @retval SR_OK Success.
 * @retval SR_ERR_ARG Invalid arguments.
 * @retval SR_ERR Device instance was already active, or other error.
 *
 * @since 0.2.0
 */
SR_API int sr_dev_open(struct sr_dev_inst *sdi)
{
        int ret;

        if (!sdi || !sdi->driver || !sdi->driver->dev_open)
                return SR_ERR_ARG;

        if (sdi->status == SR_ST_ACTIVE) {
                sr_err("%s: Device instance already active, can't re-open.",
                        sdi->driver->name);
                return SR_ERR;
        }

        sr_dbg("%s: Opening device instance.", sdi->driver->name);

        ret = sdi->driver->dev_open(sdi);

        if (ret == SR_OK)
                sdi->status = SR_ST_ACTIVE;

        return ret;
}

/**
 * Close the specified device instance.
 *
 * If the device instance is not open (sdi->status != SR_ST_ACTIVE),
 * SR_ERR_DEV_CLOSED will be returned and no closing will be attempted.
 *
 * Note: sdi->status will be set to SR_ST_INACTIVE, regardless of whether
 * there are any errors during closing of the device instance (any errors
 * will be reported via error code and log message, though).
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @retval SR_OK Success.
 * @retval SR_ERR_ARG Invalid arguments.
 * @retval SR_ERR_DEV_CLOSED Device instance was not active.
 * @retval SR_ERR Other error.
 *
 * @since 0.2.0
 */
SR_API int sr_dev_close(struct sr_dev_inst *sdi)
{
        if (!sdi || !sdi->driver || !sdi->driver->dev_close)
                return SR_ERR_ARG;

        if (sdi->status != SR_ST_ACTIVE) {
                sr_err("%s: Device instance not active, can't close.",
                        sdi->driver->name);
                return SR_ERR_DEV_CLOSED;
        }

        sdi->status = SR_ST_INACTIVE;

        sr_dbg("%s: Closing device instance.", sdi->driver->name);

        return sdi->driver->dev_close(sdi);
}

/**
 * Queries a device instances' driver.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The driver instance or NULL on error.
 */
SR_API struct sr_dev_driver *sr_dev_inst_driver_get(const struct sr_dev_inst *sdi)
{
        if (!sdi || !sdi->driver)
                return NULL;

        return sdi->driver;
}

/**
 * Queries a device instances' vendor.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The vendor string or NULL.
 */
SR_API const char *sr_dev_inst_vendor_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->vendor;
}

/**
 * Queries a device instances' model.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The model string or NULL.
 */
SR_API const char *sr_dev_inst_model_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->model;
}

/**
 * Queries a device instances' version.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The version string or NULL.
 */
SR_API const char *sr_dev_inst_version_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->version;
}

/**
 * Queries a device instances' serial number.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The serial number string or NULL.
 */
SR_API const char *sr_dev_inst_sernum_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->serial_num;
}

/**
 * Queries a device instances' connection identifier.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return A copy of the connection ID string or NULL. The caller is responsible
 *         for g_free()ing the string when it is no longer needed.
 */
SR_API const char *sr_dev_inst_connid_get(const struct sr_dev_inst *sdi)
{
#ifdef HAVE_LIBUSB_1_0
        struct drv_context *drvc;
        int cnt, i, a, b;
        char conn_id_usb[64];
        struct sr_usb_dev_inst *usb;
        struct libusb_device **devlist;
#endif

#ifdef HAVE_SERIAL_COMM
        struct sr_serial_dev_inst *serial;
#endif

        struct sr_scpi_dev_inst *scpi;
        char *conn_id_scpi;

        if (!sdi)
                return NULL;

#ifdef HAVE_SERIAL_COMM
        if ((!sdi->connection_id) && (sdi->inst_type == SR_INST_SERIAL)) {
                /* connection_id isn't populated, let's do that for serial devices. */

                serial = sdi->conn;
                ((struct sr_dev_inst *)sdi)->connection_id = g_strdup(serial->port);
        }
#endif

#ifdef HAVE_LIBUSB_1_0
        if ((!sdi->connection_id) && (sdi->inst_type == SR_INST_USB)) {
                /* connection_id isn't populated, let's do that for USB devices. */

                drvc = sdi->driver->context;
                usb = sdi->conn;

                if ((cnt = libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist)) < 0) {
                        sr_err("Failed to retrieve device list: %s.",
                               libusb_error_name(cnt));
                        return NULL;
                }

                for (i = 0; i < cnt; i++) {
                        /* Find the USB device by the logical address we know. */
                        b = libusb_get_bus_number(devlist[i]);
                        a = libusb_get_device_address(devlist[i]);
                        if (b != usb->bus || a != usb->address)
                                continue;

                        if (usb_get_port_path(devlist[i], conn_id_usb, sizeof(conn_id_usb)) < 0)
                                continue;

                        ((struct sr_dev_inst *)sdi)->connection_id = g_strdup(conn_id_usb);
                        break;
                }

                libusb_free_device_list(devlist, 1);
        }
#endif

        if ((!sdi->connection_id) && (sdi->inst_type == SR_INST_SCPI)) {
                /* connection_id isn't populated, let's do that for SCPI devices. */

                scpi = sdi->conn;
                sr_scpi_connection_id(scpi, &conn_id_scpi);
                ((struct sr_dev_inst *)sdi)->connection_id = g_strdup(conn_id_scpi);
                g_free(conn_id_scpi);
        }

        return sdi->connection_id;
}

/**
 * Queries a device instances' channel list.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The GSList of channels or NULL.
 */
SR_API GSList *sr_dev_inst_channels_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->channels;
}

/**
 * Queries a device instances' channel groups list.
 *
 * @param sdi Device instance to use. Must not be NULL.
 *
 * @return The GSList of channel groups or NULL.
 */
SR_API GSList *sr_dev_inst_channel_groups_get(const struct sr_dev_inst *sdi)
{
        if (!sdi)
                return NULL;

        return sdi->channel_groups;
}

/** @} */